The presence of H3K4me3 histone mark is positively correlated with expression at the DAM loci in sweet cherry during dormancy

In perennial species such as sweet cherry, dormancy is a period of repressed growth that acts to protect sensitive tissues during unfavourable climatic conditions. Dormancy and bud burst are strongly affected by temperature. The mean surface temperature of the earth is increasing and this climatic change may have negative consequences on the dormancy release and result in lower cherry production. Despite this well-described effect of temperature on phenology, the molecular events regulating dormancy are still poorly understood. It has been shown that the expression of DORMANCY-ASSOCIATED MADS-box (DAM)-related genes is up-regulated in dormant buds and inversely down-regulated in non-dormant buds in several perennial plant species (peach, pear, leafy spurge, apple). Recent studies suggested the role of epigenetic mechanisms, such as DNA methylation and chromatin modifications, in the regulation of bud dormancy and dormancy release. To better understand the mechanisms underlying the effect of temperature on dormancy we assessed genome-wide dynamics of one chromatin mark (H3K4me3) associated with open chromatin and gene activation. It was coupled with expression analysis during dormancy in floral buds of sweet cherry cultivar 'Burlat' (Prunus avium L.). We detected transcriptional and histone methylation dynamics of dormancy-related genes (PavDAM5 and PavDAM6) during the dormancy cycle.